Riotintobolus mandenensis Wesener, 2009

Wesener, Thomas, Enghoff, Henrik & Sierwald, Petra, 2009, Review of the Spirobolida on Madagascar, with descriptions of twelve new genera, including three genera of ' fire millipedes' (Diplopoda), ZooKeys 19 (19), pp. 1-128 : 51-52

Riotintobolus mandenensis Wesener , sp. n.

urn:lsid:zoobank.org:act:7C0503C7-C70F-4FA4-A9A8-4E9F049E5391

Material examined: 1 ♂, 16 ♀, 20 imm. Holotype: 1 ♂ (36 mm long, dissected), FMMC W040 C, Province Toliara, Mandena , littoral forest on sand, 34 m, 24°57.260’ S, 46°59.499’ E, leg. T. Wesener et al., 02.VI.2007 . Paratypes: 5 ♀, 5 imm., FMMC W039 C, same data as holotype ; 1 ♀, 2 imm., CAS W039 C, same data as holotype ; 1 ♀, 2 imm., ZMUC W39 C, same data as holotype ; 1 ♀, 2 imm., ZMH W39 C, same data as holotype ; 1 ♀, 2 imm., ZSM W039 C, same data as holotype .

Other material examined: 7 ♀, 7 imm., W039C, same data as holotype, University Antananarivo.

Differential diagnosis: the size and special colour pattern are unique for Malagasy millipedes. The gonopods of this species are similar in some aspects to those of R. minutus sp. n. and R. anomalus sp. n., but the posterior gonopods are of a unique shape.

Description. Measurements: holotype with 41 podous and 2 apodous rings, 36 mm long, 3.1 mm wide. Females with 41–43 podous and 0–2 apodous body rings, 37–43 mm long, 4.2–4.4 mm wide.

Coloration black, dorsally with an extraordinary wide, light brown stripe ( Fig. 24A ). Posterior half of collum dorsally black ( Fig. 26A ). Head, legs and antennae light brown. Eyes with 16–20 almost fused ocelli arranged in 4 or 5 rows ( Figs 26A, C ). Antennae protruding back to body ring 2 ( Fig. 26A ). Legs without tarsal pads. Male legs reach 0.7 times, female legs 0.6 times body diameter. Preanal process sharp-edged, straight, protruding above anal valves ( Fig. 26B ). Anal valves small, between anterior part and lips with a deep groove, margin towards groove sharpedged ( Fig. 26B ).

Anterior gonopod sternite basally wide, apically elevated into a lobe with a triangular, well-rounded tip ( Fig. 26I ). Sternite tip almost as high as mesal process of coxite; latter relatively slender, elongated, longer than sternite ( Fig. 26I ). Telopodite on posterior side apically with a large triangular, retrorse process ( Fig. 26K ). Process projecting above coxite and telopodite ( Fig. 26K ).

Posterior gonopods telopodite laterally with a single, large, finger-shaped process ( Fig. 26J, x ). Second small projection, where sperm canal is discharging, is located close to apex ( Fig. 26M, y ). A large, bi-lobical membrane present apically. Membrane apically three times wider than basally ( Fig. 26L, z ). A small, white, swollen area ( Fig. 26M ) is also located basally of membrane.

Intraspecific variation: females exist in different size classes. The presence of apodous rings in front of the telson in mature specimens hint to the existence of postmaturity moults.

Distribution and ecology: this species was only collected in the littoral rainforest on sand of Mandena ( Fig. 25 ). Only 160 ha of this forest will remain after a large-scale mining project ( Vincelette et al. 2003). All specimens were collected directly on the root layer under a thin layer of leaf litter. Disturbed specimens often did not curl into a spiral but remained motionless and stiff like a stick even when picked up. Because of their black/light-brown colour pattern ( Fig. 24A ), specimens of R. mandenensis were quite difficult to detect against the background consisting of sand with some darker top soil inclusion. The giant pill-millipede species Sphaeromimus inexpectatus Wesener & Sierwald, 2005 is also only known from a small area surrounding Mandena (Wesen- er and Sierwald 2005).

Etymology: mandenensis , adjective, refers to the only area where this species lives, the littoral forest of Mandena.

Figures

Figure 24. A Riotintobolus mandenensis sp. n., living specimens B pseudosteppe and burned shrubs dominating the area between the littoral forests of Mandena and Sainte Luce, SE Madagascar C Sainte Luce littoral forest, manioc plantation and destroyed trees inside conservation zone S8.

Figure 25. Distribution of the genus Riotintobolus gen. n.

Figure 26. Riotintobolus mandenensis sp. n., A, B, I–M male holotype, C–H female paratype. A head, lateral view B telson C head, detail of incisura lateralis D head, frontal view E second leg with vulva F gnathochilarium, overview G gnathochilarium, detail of mentum H left mandible, mesal view I anterior gonopod, anterior view Į left posterior gonopod, anterior view K anterior gonopod, posterior view L telopodite of left posterior gonopod, posterior view M left posterior gonopod, overview, posterior view. 3iT = 3-combed internal tooth; av = anal valves; Co = collum; Cx = coxite; eT = external tooth; Gn = gnathochilarium; Gr = groove; IL = incisura lateralis; L = ledge; LL = lamella linguales; LT = lateral tooth; Md = mandible; Me = mentum; mp = molar plate; pL = pectinate lamella; Pre = preanal ring; sf = setiferous foveolae; St = sternite; ST = stipites; sub = subanal scale; T = telopodite; Vu = vulva. Scale bars = 1 mm.